Post-mix beverages are generally supplied to the point of sale in concentrated form and are mixed in a container mounted on or connected to a dispenser. Pre-mix beverages are simply poured into the container ready for dispensing. This is known as an open ended system. Any beverage which has a tendency to separate or stratify must be agitated prior to being dispensed. Conventional open ended systems use, for example, an impellor, a paddle wheel or pump circulation to effect the agitation and prevent sedimentation. Such systems are described in U.S. Pat. Nos. 4,610,145, 3,664,643 and 4,008,832.
One serious problem with the aforementioned systems is that the beverages must be decanted into the mixing container in the dispenser. To ensure that bacteria and the like do not effect the quality of the beverage it is important that the container and agitating means are cleaned and sterilized regularly. In practice this is often not done and, particularly where a beverage remains in the mixing container for long periods, the quality of the beverage suffers. In fact, by simply decanting the beverage from the sealed and sterilized container in which it is is supplied, the beverage comes into contact with the ambient atmosphere and hence any bacteria which might be present therein. To counter this problem, most beverage suppliers add preservatives to their beverages in order to improve the shelf life of the beverages.
Many people object to the presence of preservatives in their beverages. It is known to supply naturally preserved fruit juices and like beverages in "bag-in-box" type containers which include a collapsible bag which is designed to collapse as the beverage is dispensed. This could be called a closed system. A major advantage of this sytem is that no air is brought into contact with the beverage during dispensing resulting in a far longer shelf life. Clearly, this principle is unsuited for prior art pre-mix commercial dispensers where the beverage to be dispensed is not homogeneous, as the necessary agitators cannot be brought into contact with the liquid. The stratification of the liquid will result in a variation of the consistency of the dispensed beverage.
It is accordingly an object of this invention to provide a fluid dispenser with which the aforementioned problems may be overcome or at least minimised.